Igniter squib



Sept. 13, 1966 R. E. BE'rTs ETAL IGNITER SQUIB Filed Aug. 5

Robert E. Befls Nathan P. Williams.

INVENToRs. W m. BYE-4'='`'M tj, W

JW M W w, w"

United States Patent O 3,272,127 IGNITER SQUIB Robert E. Betts and Nathan P. Williams, I-iuntsville, Ala., assignors to the United States of America as represented by the Secretary of the Army Filed Aug. 5, 1963, Ser. No. 300,114 5 Claims. (Cl. 102-702) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royialty thereon.

This invention relates to an ignitor squib and more particularly to an improved ignitor squib of the general class disclosed in an application filed by Robert E. Betts for Ignitor Squib filed August 31, 1960, Serial Number 53,314, and now Patent No. 3,100,447.

It is an object of this invention to provide an improved ignitor squib of the indicated class.

Another object of this invention is to provide an ignitor squib wherein products of bridge wire ignition are concentrated on a desired portion of the py-rotechnic.

These and other objects of the invention will become more apparent upon consideration of the following detailed description and accompanying drawing which is a perspective view, partly in section, of the ignitor squib.

In the illustrat-ion the ignitor squib is shown to include a housing 12 having a closed end 14 and an open end 16. Open end 16 lis adapted to receive a pheno'lic bridge plug 20. One end 22 of the plug is reduced so as to provide an annular space 23 between the plug and the sides of housing 12.

To provide an electnical connection to the squib, a pair of crimped lead wires 24 are molded in plug 20 so that they do not extend beyond the face 19 of end 22, of plug 20. These wires are joined at the ends 21 thereof by a resistance containing bridge Wire 25. The bridge wire extends adjacent the face 19 of plug 20' and connects to wires 24. The other end of wires 24 are covered by suitable insulat'ing material 26 which is molded in plug 20v A pyrotec-hnic 30 is retained in the closed end 14 of the housing by a cup-shaped diaphragm 32 and a cupshaped metal die 38. The diaphragm is force-fitted with housing 12 and is spaced from end 22 of plug 20. Diaphragm 32 acts a Faraday shield, protecting the pyrotechnic from ignition by static charges passing through or building up on the surface of material 30. Base portion 34 of the diaphragm is provided with a center section having a dimple 36 formed therein.

Die 3-8 is form fitted within diaphragm 32 and includes a base 40 and a periphera'l wall 42. Base 40 has a central hole 41 formed therethrough concentric with dimple 36 for purposes explained hereinbelow. Wall 42 is disposed to direct the exploding force of the pyrotechnic 30 out through the end 14 of housing 12.

An element 50, formed of a d-ieleotric material, is placed between plug 20 and diaphragm 32. The function of element 50 is threefold; to insure diaphragm 32 remains spaced from plug end 22, to prevent arcing between the bridge wire and the diaphragm, and to concentrate the products of bridge Wire ignition on the diaphram. Element 50 is substantially cup-shaped having a base 52 and a downward projecting wall 54. The element is disposed so as to have its base 52 adjacent diaphragm base 34 and its wall 54 extended into annular space 23. An annular lip 56 formed in element Wall 54 seats the element on the face of plug end 22. A dielectric se'alant 58 bonds the element to plug 20. The disposition of element 50 de'firres a compartment 60 encl'osed by element wall 54, element base 5-2 and the face of plug end 22. A bore 55 defines a passage through the element base to the area of dimple 36.

ICC

To prevent arcing from the bridge wire through the bore in element 50 to the diaphragm, an insulator 62 is disposed between element 50 and the diaphr'agm and extends across the bore. And to provide a means for the discharge of static electricity from the ignitor, a plurality of air ga-ps 57 are formed in the phenol plug 20 and are disposed in communication with the lead wires 24 and housing 12, to form a path of lowe'st resistance between the housing and lead wires.

The ignitor squib is mounted in any known manner and the power for Operating the squib and the control means (not shown) are connected to lead wires 24. Power for exploding the bridge wire of an embodiment having, for example, a bridge wire of .1 ohm resistance, can be achieved by charging a one m'icrofarad capacitor to 2000 volts. The capacitor is then d-ischarged to the bridge delivering a voltage in excess of 500 volts in approximately one microsecond and a current density of one million iampheres per square centimeter of cross sectional bridge Wire area.

The squib is actuated by operation of the control means which lconnects an electrical source to the bridge wire. When the required electrical energy reaches the bridge wire it is converted to heat, thereby developing pressure in the bridge wire and compartment. This action causes the bridge wire to explode increasing the heat and pressure in compartment 60. This heat and pressure is then directed by bore 55 to the diaphnagm. As the area of bore 55 is relatively small compared to the area of compartment 60, the force produced by the heat and pressure is intensified. This intensified force, after first rupturing insulator 62, encounters the lower area of dimple 3.6. The dimple is forced, by the heat and pressure, to exp'and upward through hole 41 to she-ar against die 38. Shearing of dimple 36 allows heat and pressure from the exploding 'bridge wire to contact the pyrotechnic.

The burning pyroteohnc then produces heat and pressure within the squib. The die wall 42 efiectively contains the lateral pressure forces produced by the burning pyrotechnic and direct-s .the total heat and pressure force -to the closed end 14 of housing 12. The closed end is then ruptured for'cing hot gases and burning particles into contact with surrounding material.

'As the volume of compartment 60 is a .factor in determining the pressure produced by the burning bridge Wire, various modifieations can be made in the configuration of focusing element 50 to control pressure in the c'ompartment. For example, the surface of element base '52 forming the top of compartment 60 can be gener'ally dome-shaped to increase oompartment Volume. A dome or surface inclined |toward bore 55 would also provide a means to direct the products of bridge wire ign-ition to the bore.

Thus it will be appreciated that this invention provides an improved ignitor squib of the class indicated.

It is also to be understood that various modifications of the ignitor squib descri'bed herein can be resorted to 'that is within the spirit and scope of the appended claims.

The invention claimed is:

1. An improved igni-ter squib comprising:

(a) `a housing having a closed end and an open end;

(b) a metal container having a pyrotechnic therein disposed in said housing adjacent said closed end rand cooperating therewith for complete enclosure of said pyrotechnic for shielding thereof from static charges;

(c) -a bridge plug extending into said housing through said open end;

(d) a firing circuit carried by said plug including a pair of lead wires extending through said plug and into said housing, and a bridge wire carried by 'said plug |and connected to said lead wires, said 3 bridge wire being disposed in spaced relation with said pyrotechnic;

(e) focusing means carried in said housing and dis- Iposed for concentrating the igniting energy from said bridge wire to said pyrotechnic responsive to a predetermined build-up of said igniting energy, said focusing means including a substantially cup-shaped member 'of dieleotric material having the wall thereof partially surrounding said bridge plug ;and

4. An improved igniter squib comprising:

(a) a housing;

(b) 'a pyrotechnic material disposed in said housing;

(c) a diiaphriagm mounted in said housing for support of said pyrotechnic material, said diaphragm being cup-shaped and having the wall thereof force fitted with said housing and partially enclosing said pyrotechnic material and provided with a base hav- -ing 'a rupturable portion in the form 'of |a dimple is wntrallyV located int Said basedisposed ftherein;

(d) a firing circuit extending into said housing in spaced relation with said diaphragm; and,

(e) a member interposed between said diap'hragm and said pyrotechnic material and provided with a bore V'adjaent said VVrupturable portion to serve 'as fa die77V i against which said rupturable portion can shear responsive to energization of said firing circuit to concentrate substantially total ignition energy to said pyrotechnic.

5. A device as set forth in claim 4 in which:

(a) said die is cup-shaped to form fit with said diaphragm and includes za base having said bore centrally disposed therethrough; .and

(b) said dimple disposed in m-ating contact with the i periphery of said bore to shear thereagainst responisive to ignition of said firing circuit.

the base thereof adjacent said pyrotechnic, said base 10 having a bore therethrough for directing the ignition energy from said bridge wire to said pyrotechnic.

2. A device as set forth in claim 1 in which said bore 3. An improved igniter squib comprising:

(a) a housing having a head end and an open end;

(b) a pyr-otechnic disposed in said head end;

(c) a cup-shaped retaining member mounted in said head end for retention of said pyrotechnic between 20 said head end and said retaining member;

(d) 'a bridge plug extending int'o said housing through said open end and provided with 'a face disposed in spaced relation with said cup-shaped retaining member;

(e) a bridge wire carried on said face of said bridge plug and connected to .a source of energy for ener- References Cted by the Examiner at` t l d f b i izlfolirz: hoerrfrljiotll e said rldge Wire and produce UNITED STATES PATENTS (f) force focusing means including a substantially 2,772533 12/1956 Barocca 102 28 cup-shaped spacer provided with a base having a 2301,585 8/1957 Smith 102 28 i bore therethrough, said cup-shaped spacer disposed 2386,090 5/1961 Doeppinghaus 102 23 1 adjacent said retaining member and provided with 3,090,308 5/1963 Paschoud 102 28 'an annular wall depending from said base and par- 3,090,310 5/1963 Peet et al. IDZ- 70.2 X tially enclosing 'said bridge plug to form a compart- 3,100,447 8/1963 Betts 102-28 ment between said bridge plug and said spacer; 3,134,329 5/ 1964 Zeman 102-'28 i (g) said compartment being closed by the face of said bridge plug; and

(h) said bridge wire being disposed in said compartment.-

BENJAMIN A. BoRcHELT, Prz'mzz'y Examz'ner. l

40 sAMUEL FEINBERG, Examz'ner.

L. L. HALLACHER, W. C. ROCH, Assistant Examiners. 

4. AN IMPROVED IGNITER SQUIB COMPRISING: (A) A HOUSING; (B) A PYROTECHNIC MATERIAL DISPOSED IN SAID HOUSING; (C) A DIAPHRAGM MOUNTED IN SAID HOUSING FOR SUPPORT OF SAID PYROTECHNIC MATERIAL, SAID DIAPHRAGM BEING CUP-SHAPED AND HAVING THE WALL THEREOF FORCE FITTED WITH SAID HOUSING AND PARTIALLY ENCLOSING SAID PYROTECHNIC MATERIAL AND PROVIDED WITH A BASE HAVING A RUPTURABLE PORTION IN THE FORM OF A SIMPLE DISPOSED THEREIN; (D) A FIRING CIRCUIT EXTENDING INTO SAID HOUSING IN SPACED RELATION WITH SAID DIAPHRAGM;AND, (E) A MEMBER INTERPOSED BETWEEN SAID DIAPHRAGM AND SAID PYROTECHNIC MATERIAL AND PROVIDED WITH A BORE ADJACENT SAID RUPTURABLE PORTION TO SERVE AS A DIE AGAINST WHICH SAID RUPTURABLE PORTION CAN SHEAR RESPONSIVE TO ENERGIZATION OF SAID FIRING CIRCUIT TO CONCENTRATE SUBSTANTIALLY TOTAL IGNITION ENERGY TO SAID PYROTECHNIC. 